Feasibility Study of Removing the Grand Rapids-Providence Dams, Maumee River (NW Ohio) Based on HEC-RAS Models

by Mueller, Zachery P.

Abstract (Summary)

The Providence and Grand Rapids dams, located on the Maumee River at Grand Rapids, Ohio are low-head dams built in 1840 as rock-crib dams that were subsequently bolstered with concrete in 1907. The Providence dam is 362.1 m long and 2.6 m tall while the Grand Rapids dam is 195.7 m long and 2.4 m tall. Both dams create a single reservoir with a normal pool storage of 1233.5 m3 which is used for water supply and recreation. This study investigated the impacts to the flood regime in the area associated with the removal of the two dams by comparing HEC-RAS models of pre- and post-dam removal scenarios with 10-, 25-, 50-, 100-, 200-, 500-year flooding events. The model encompassed 30.6 river kilometers of the Maumee River located in Henry, Lucas, and Wood County, Ohio using a total of 64 cross-sections collected from HEC-GeoRAS and a 1998 HEC-6 sediment transport model along with 20 interpolated cross-sections created by HEC-RAS. The research also examined the potential release of sediment trapped behind the dams by performing grain-size analysis of sediment collected upstream of the dams.
The HEC-RAS results showed no significant change in the flood regime upstream of the dams and no change at all downstream of the dams. Immediately upstream of the dams the water surface elevation decreased from an initial elevation of 644.82 ft to 644.64 ft for the 10-year flooding event, a difference of less than
The potential release of sediment trapped behind the dams was determined to be low due to the low trapping efficiency of the dams determined from observations of essentially no sediment accumulation in the reservoir. Along with the low trapping efficiency of the dams, the majority of the sediment being transported by the Maumee River was determined to be largely mud which is transported as suspended load and carried over the dams.
These results showed no significant changes in the flood regime near Grand Rapids, Ohio and no risk of releasing large quantities of sediment downstream after dam removal.